1,3-pentadiene derivatives and electrophotographic photoconductor using the same

ABSTRACT

A charge transporting material comprising a 1,3-pentadiene derivative having formula (I): 
     
         A--CH═CH--CH═CH--CH.sub.2 --A                      (I) 
    
     wherein A represents a 9-anthryl group which may have a substituent, a N-substituted carbazolyl group which may have a substituent, a N-substituted phenothiazinyl group which may have a substituent or ##STR1## in which Ar represents an arylene group which may have a substituent, R 1  and R 2  each represent an alkyl group which may have a substituent, an aralkyl group which may have a substituent, or an aryl group which may have a substituent; an electrophotographic photoconductor comprising an electroconductive support and a photoconductive layer formed thereon, which comprises as an effective component at least one of the 1,3-pentadiene derivatives of the above formula (I); and novel 1,3-pentadiene derivatives of the formula (I), provided that in the formula (I), R 1  and R 2  cannot be a methyl group at the same time, are disclosed.

This application is a continuation of application Ser. No. 07/342,970filed on Apr. 25, 1989, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to 1,3-pentadiene derivatives and anelectrophotographic photoconductor which comprises a photoconductivelayer comprising at least one of the 1,3-pentadiene derivatives.

2. Discussion of Background

Some examples of photoconductive materials for use in the conventionalphotoconductors used in electrophotography include inorganic materialssuch as selenium, cadmium sulfide and zinc oxide. In anelectrophotographic process, a photoconductor is first exposed to coronadischarge in the dark, so that the surface of the photoconductor iselectrically charged in a uniform manner. The thus uniformly chargedphotoconductor is then exposed to original light images and the exposedportions selectively become electroconductive, causing the dissipationof electric charges from these portions of the photoconductor. Latentelectrostatic images, corresponding to the original light images, arethus formed on the surface of the photoconductor. The latentelectrostatic images are then developed by a so-called "toner" whichcomprises a colorant, such as a dye or a pigment, and a binder agentmade of a polymeric material. Through this process, visible, developedimages can be obtained on the photoconductor.

The fundamental requirements of a photoconductor for use inelectrophotography are: (1) chargeability to a predetermined potentialin the dark; (2) minimal electric charge dissipation in the dark; and(3) rapid dissipation of electric charges upon exposure to light.

While the above-mentioned inorganic photoconductive materials have manyadvantages over other conventional photoconductive materials, they alsohave several drawbacks. For example, the selenium photoconductor, whichis widely used at present and sufficiently meets the above-mentionedrequirements (1) to (3), is also characterized by difficult methodswhich ultimately result in increased production costs. The properties ofthe material itself are less than desirable. Its low flexibility hindersthe process of forming it into a belt. As well, its vulnerability tothermal and mechanical shocks necessitates extremely careful materialhandling.

Cadmium sulfide photoconductors and zinc oxide photoconductors areprepared by dispersing cadmium sulfide or zinc oxide in a binder resin.Due to this dispersive condition, the mechanical properties of theresulting material are poor such as surface smoothness, hardness,tensile strength and wear resistance. Thus these materials are notsuitable for use as photoconductors where much repetition isencountered, such as in plain paper copiers.

Recently, varieties of organic electrophotographic photoconductors havebeen proposed to cover the shortcomings of the inorganic photoconductor.Some of them are now being used in practice. Representative examples ofthe organic electrophotographic photoconductor include one that iscomprised of poly-N-vinylcarbazole and 2,4,7-trinitrofluorene-9-on U.S.Pat. No. 3,484,237), a photoconductor in which poly-N-vinylcarbazole issensitized by a pyrylium salt type dyestuff (Japanese Patent Publication48-25658), a photoconductor containing a main component of organicpigment (Japanese Laid-Open Patent Application 47-37543), and aphotoconductor containing as the main component, an eutectic crystallinecomplex made of a dye and a resin (Japanese Laid-Open Patent Application47-10735).

Although the above-mentioned organic electrophotographic photoconductorshave many superior in many respects to other conventionalphotoconductors, they do not satisfy all the requirements of anelectrophotographic photoconductor.

SUMMARY OF THE INVENTION

It is therefore a first object of the present invention to provide novel1,3-pentadiene derivatives, which may be employed in electrophotographicphotoconductors.

A second object of the present invention is to provide anelectrophotographic photoconductor from which the previously mentionedconventional shortcomings are eliminated, and which can meet all therequirements of an electrophotographic photoconductor in terms of thefundamental electrophotographic characteristics.

A third object of the present invention is to provide anelectrophotographic photoconductor which has high flexibility anddurability and can be easily manufactured at a low cost.

The first object of the present invention can be achieved by1,3-pentadiene derivatives having the following formula (I):

    A--CH═CH--CH═CH--CH.sub.2 --A                      (I)

wherein A represents a 9-anthryl group which may have a substituent, aN-substituted carbazolyl group which may have a substitutent, aN-substituted phenothiazinyl group which may have a substituent or##STR2## in which Ar represents an arylene group which may have asubstituent, R¹ and R² each represent (i) an alkyl group which may havea substituent, provided that R¹ and R² cannot be a methyl group at thesame time, (ii) an aralkyl group which may have a substituent, or (iii)an aryl group which may have a substituent.

The second and third objects of the present invention can be attained byan electrophotographic photoconductor comprising an electroconductivesupport and a photoconductive layer formed thereon, which comprises asan effective component at least one of 1,3-pentadiene derivatives of theabove formula (I), in which R¹ and R² may be a methyl group at the sametime.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 is an infrared spectra of 1,3-pentadiene derivative obtained inSynthesis Example 1;

FIG. 2 is a schematic cross-sectional view of a first embodiment of anelectrophotographic photoconductor according to the present invention;

FIG. 3 is a schematic cross-sectional view of a second embodiment of anelectrophotographic photoconductor according to the present invention;

FIG. 4 is a schematic cross-sectional view of a third embodiment of anelectrophotographic photoconductor according to the present invention;

FIG. 5 is a schematic cross-sectional view of a fourth embodiment of anelectrophotographic photoconductor according to the present invention;and

FIG. 6 is a schematic cross-sectional view of a fifth embodiment of anelectrophotographic photoconductor according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As mentioned previously, the 1,3-pentadiene derivatives according to thepresent invention have the following formula (I):

    A--CH═CH--CH═CH--CH.sub.2 --A                      (I)

wherein A represents a 9-anthryl group which may have a substituent, aN-substituted carbazolyl group which may have a substituent, aN-substituted phenothiazinyl group or ##STR3## in which Ar represents anarylene group which may have a substituent, R¹ and R² each represent analkyl group which may have a substituent, provided that R¹ and R² cannotbe a methyl group at the same time, an aralkyl group which may have asubstituent, an aralkyl group which may have a substituent, or an arylgroup which may have a substituent.

In the above formula (I), an example of the substituent of the 9-anthrylgroup is a halogen such as bromine; examples of the substituent of theN-substituted carbazolyl group include an alkyl group having 1 to 4carbon atoms which may have a substituent such as a halogen and ahydroxyl group, and a phenyl group which may have a substituent such asan alkyl group having 1 to 4 carbon atoms and an alkoxyl group having 1to 4 carbon atoms; examples of the substituent of the N-substitutedphenothiazinyl group include an alkyl group having 1 to 4 carbon atoms;examples of the substituent of the arylene group represented by Arinclude an alkyl group having 1 to 4 carbon atoms, and an alkoxyl grouphaving 1 to 4 carbon atoms; examples of the alkyl group represented byR¹ or R² include an alkyl group having 1 to 4 carbon atoms, which mayhave a substituent such as an unsubstituted or substituted phenyl group;examples of the substituent of the aralkyl group or aryl grouprepresented by R¹ or R² include an alkyl group having 1 to 4 carbonatoms, an alkoxyl group having 1 to 4 carbon atoms, a halogen such aschlorine, and a phenyl group.

The 1,3-pentadiene derivatives having the formula (I) according to thepresent invention can be prepared by allowing a 1,3-propylenederivative, represented by the following formula (II), to react with analdehyde compound, represented by the formula (III), preferably in thepresence of a basic catalyst.

    Y--CH.sub.2).sub.3 Y                                       (II)

wherein Y represents ##STR4## in which Z.sup.⊖ represents a halogen ion;and R¹ represents a lower alkyl group.

    A--CHO                                                     (III)

wherein A represents a 9-anthryl group which may have a substituent, aN-substituted carbazolyl group which may have a substituent, aN-substituted phenothiazinyl group or ##STR5## in which Ar represents anarylene group which may have a substituent, R¹ and R² each represent analkyl group which may have a substituent, an aralkyl group which mayhave a substituent, or an aryl group which may have a substituent.

Specific examples of the basic catalyst for the above reaction includepotassium hydroxide, sodium amide, sodium methylate, potassium methylateand alcoholates such as potassium t-butoxide.

Specific examples of the reaction solvent are methanol, ethanol,propanol, toluene, xylene, dioxane, N,N-dimethylformamide, dimethylsulfoxide, and tetrahydrofuran.

The temperature for the above reaction can be set in a relatively widerange. This range depends on (1) the stability of the solvent employedin the presence of the basic catalyst, (2) the reactivities of thecondensation components, (that is, the compounds of the formulas (II)and (III)), and (3) the reactivity of the basic catalyst in the solventemployed, which works as a condensation agent in this reaction.

When a polar solvent is, for example, employed as the reaction solvent,the reaction temperature can be set in the range of room temperature toabout 100° C., preferably in the range of room temperature to about 80°C. However, if a shorter reaction time is desired or a less reactivecondensation agent is employed, the reaction temperature can be elevatedbeyond this range.

The above-mentioned 1,3-propylene derivatives of the formula (II) whichserves as a starting material for the production of the 1,3-pentadienederivatives according to the present invention can be easily produced.For example, one method is to allow a 1,3-dihalogenopropylene compoundto directly react with trialkyl phosphite or triphenylphosphine underthe application of heat. Alternatively, the above-mentioned reaction maybe carried out in an organic solvent such as toluene, xylene ordimethylformamide.

As previously mentioned, the electrophotographic photoconductoraccording to the present invention comprises a photoconductive layercomprising as an effective component at least one of 1,3-pentadienederivatives represented by the formula I) in which R¹ and R² may be amethyl group and the same time.

These 1,3-pentadiene derivatives can either be optically or chemicallysensitized by sensitizers such as dyes and Lewis acids. Furthermore, theabove-mentioned 1,3-pentadiene derivatives are particularly useful ascharge transporting materials employed in the function-separating typephotoconductor which uses an organic or inorganic pigment as a chargegenerating material.

Specific examples of the above-mentioned 1,3-pentadiene derivatives foruse in the electrophotographic photoconductor according to the presentinvention are as follows:

                                      TABLE 1                                     __________________________________________________________________________    [ACHCHCHCHCH.sub.2A]                                                                  1,3-pentadien                                                                 derivative No.                                                                        A                                                             __________________________________________________________________________            1                                                                                      ##STR6##                                                             2                                                                                      ##STR7##                                                             3                                                                                      ##STR8##                                                             4                                                                                      ##STR9##                                                             5                                                                                      ##STR10##                                                            6                                                                                      ##STR11##                                                            7                                                                                      ##STR12##                                                            8                                                                                      ##STR13##                                                            9                                                                                      ##STR14##                                                            10                                                                                     ##STR15##                                                            11                                                                                     ##STR16##                                                            12                                                                                     ##STR17##                                                            13                                                                                     ##STR18##                                                    __________________________________________________________________________     ##STR19##                                                                    1,3-pentadien                                                                 derivative No.                                                                        Ar            R.sup.1       R.sup.2                                   __________________________________________________________________________    14                                                                                     ##STR20##    CH.sub.3      CH.sub.3                                  15                                                                                     ##STR21##    C.sub.2 H.sub.5                                                                             C.sub.2 H.sub.5                           16                                                                                     ##STR22##    C.sub.2 H.sub.5                                                                             C.sub.2 H.sub.5                           17                                                                                     ##STR23##    C.sub.2 H.sub.5                                                                             C.sub.2 H.sub.5                           18                                                                                     ##STR24##    C.sub.2 H.sub.5                                                                             C.sub.2 H.sub.5                           19                                                                                     ##STR25##    C.sub.2 H.sub.5                                                                             C.sub.2 H.sub.5                           20                                                                                     ##STR26##    CH.sub.3                                                                                     ##STR27##                                21                                                                                     ##STR28##    C.sub.2 H.sub.5                                                                              ##STR29##                                22                                                                                     ##STR30##                                                                                   ##STR31##                                                                                   ##STR32##                                23                                                                                     ##STR33##                                                                                   ##STR34##                                                                                   ##STR35##                                24                                                                                     ##STR36##                                                                                   ##STR37##                                                                                   ##STR38##                                25                                                                                     ##STR39##                                                                                   ##STR40##                                                                                   ##STR41##                                26                                                                                     ##STR42##                                                                                   ##STR43##                                                                                   ##STR44##                                27                                                                                     ##STR45##                                                                                   ##STR46##                                                                                   ##STR47##                                28                                                                                     ##STR48##                                                                                   ##STR49##                                                                                   ##STR50##                                29                                                                                     ##STR51##                                                                                   ##STR52##                                                                                   ##STR53##                                30                                                                                     ##STR54##                                                                                   ##STR55##                                                                                   ##STR56##                                31                                                                                     ##STR57##                                                                                   ##STR58##                                                                                   ##STR59##                                32                                                                                     ##STR60##                                                                                   ##STR61##                                                                                   ##STR62##                                33                                                                                     ##STR63##                                                                                   ##STR64##                                                                                   ##STR65##                                34                                                                                     ##STR66##                                                                                   ##STR67##                                                                                   ##STR68##                                35                                                                                     ##STR69##                                                                                   ##STR70##                                                                                   ##STR71##                                36                                                                                     ##STR72##                                                                                   ##STR73##                                                                                   ##STR74##                                37                                                                                     ##STR75##                                                                                   ##STR76##                                                                                   ##STR77##                                38                                                                                     ##STR78##                                                                                   ##STR79##                                                                                   ##STR80##                                39                                                                                     ##STR81##                                                                                   ##STR82##                                                                                   ##STR83##                                40                                                                                     ##STR84##                                                                                   ##STR85##                                                                                   ##STR86##                                41                                                                                     ##STR87##                                                                                   ##STR88##                                                                                   ##STR89##                                42                                                                                     ##STR90##                                                                                   ##STR91##                                                                                   ##STR92##                                43                                                                                     ##STR93##                                                                                   ##STR94##                                                                                   ##STR95##                                44                                                                                     ##STR96##                                                                                   ##STR97##                                                                                   ##STR98##                                45                                                                                     ##STR99##                                                                                   ##STR100##                                                                                  ##STR101##                               46                                                                                     ##STR102##                                                                                  ##STR103##                                                                                  ##STR104##                               47                                                                                     ##STR105##                                                                                  ##STR106##                                                                                  ##STR107##                               48                                                                                     ##STR108##                                                                                  ##STR109##                                                                                  ##STR110##                               49                                                                                     ##STR111##                                                                                  ##STR112##                                                                                  ##STR113##                               50                                                                                     ##STR114##                                                                                  ##STR115##                                                                                  ##STR116##                               51                                                                                     ##STR117##                                                                                  ##STR118##                                                                                  ##STR119##                               52                                                                                     ##STR120##                                                                                  ##STR121##                                                                                  ##STR122##                               53                                                                                     ##STR123##                                                                                  ##STR124##                                                                                  ##STR125##                               54                                                                                     ##STR126##                                                                                  ##STR127##                                                                                  ##STR128##                               55                                                                                     ##STR129##                                                                                  ##STR130##                                                                                  ##STR131##                               56                                                                                     ##STR132##                                                                                  ##STR133##                                                                                  ##STR134##                               57                                                                                     ##STR135##                                                                                  ##STR136##                                                                                  ##STR137##                               58                                                                                     ##STR138##                                                                                  ##STR139##                                                                                  ##STR140##                               59                                                                                     ##STR141##                                                                                  ##STR142##                                                                                  ##STR143##                               60                                                                                     ##STR144##                                                                                  ##STR145##                                                                                  ##STR146##                               61                                                                                     ##STR147##                                                                                  ##STR148##                                                                                  ##STR149##                               62                                                                                     ##STR150##                                                                                  ##STR151##                                                                                  ##STR152##                               __________________________________________________________________________

The present invention will now be explained in detail by referring tothe following synthesis examples of the 1,3-pentadiene derivatives.

SYNTHESIS EXAMPLE 1 Synthesis of 1,3-pentadiene Derivative No. 28 inTable 1

A mixture of 55.0 g (0.075 mole) oftrimethylene-1,3-bis(triphenylphosphonium)dibromide and 41.4 g (0.15mole) of 4-N,N-diphenylaminobenzaldehyde was dissolved in 300 ml oftoluene. To this solution, 15.4 g (0.22 mole) of finely-dividedparticles of potassium methylate was gradually added at 10° C. or below.After the completion of the dropwise addition of finely-dividedparticles of potassium methylate, the solution was stirred in a streamof a nitrogen gas, with the temperature maintained at 15° C. to 18° C.for 4 hours. The obtained reaction mixture was diluted with 120 ml ofwater and the reaction product was extracted with toluene. The toluenewas partially removed from the extract solution to obtain an extract.This extract was subjected to chromatography using silica gel as acarrier and n-hexane/toluene as an eluting solution. This extract wasthen recrystallized from a mixed solvent of toluene and n-hexane,whereby 15.8 g of 1,5-bis(4-N,N-diphenylaminophenyl)-1,3-pentadiene,which is given as 1,3-pentadiene derivative No. 28 according to thepresent invention in Table 1, was obtained in the form of white crystalsin a 38% yield. The melting point of the product was at 104.5° C. to105.5° C.

The results of the elemental analysis of the thus obtained1,3-pentadiene derivative No. 28 were as follows:

    ______________________________________                                                 % C        % H    % N                                                ______________________________________                                        Calculated 88.77        6.18   5.50                                           Found      88.76        6.10   5.43                                           ______________________________________                                    

The above calculation was based on the formula for 1,3-pentadienederivative No. 28 of C₄₁ H₃₄ N₂.

An infrared absorption spectrum of the above 1,3-pentadiene derivativeNo. 28, taken using a KBr tablet, is shown in FIG. 1.

SYNTHESIS EXAMPLES 2to 9

Synthesis Example 1 was repeated except that the4-N,N-diphenylaminobenzaldehyde employed in Synthesis Example 1 wasreplaced by aldehyde compounds No. 2 to No. 9 as shown in Table 2. Thus,the 1,3-pentadiene derivatives of the present invention were obtained.

The melting points and the results of the elemental analysis of theobtained 1,3-pentadiene derivatives are also shown in Table 2.

    TABLE 2        Melting Point  Synthesis  (°C.) (Solvent Elemental Analysis     Example  for Recrystal- Found (%)/Calculated (%) No. Aldehyde Compound     1,3-pentadiene Derivative lization C H N              2      ##STR153##      ##STR154##      117-118(Toluene/n-hexane) 88.35/88.48 6.89/6.93 4.62/4.59      3     ##STR155##      ##STR156##      Oily 82.78/82.82 9.40/9.45 7.62/7.73      4     ##STR157##      ##STR158##      73-75(Toluene/n-hexane) 88.50/88.48 6.93/6.93 4.55/4.59      5     ##STR159##      ##STR160##      151.5-152  (Toluene/n-hexane) 86.97/87.18 6.33/6.65 6.20/6.16  6      ##STR161##      ##STR162##      186.0-187.0(Toluene/n-hexane) 94.17/94.25 5.73/5.75 --      7     ##STR163##      ##STR164##      74.0-76.0(Toluene/n-hexane) 76.40/76.41 5.85/5.83 5.28/5.40      8     ##STR165##      ##STR166##      Oily 82.97/83.02 9.80/9.81 7.12/7.12      9     ##STR167##      ##STR168##      89-91(n-hexane) 86.42/86.47 7.00/7.02 6.49/6.51

In the photoconductors according to the present invention, at least oneof the 1,3-pentadiene derivatives of the formula (I), in which R¹ and R²may be a methyl group at the same time, is contained in thephotoconductive layers 2a, 2b, 2c, 2d and 2e as shown in FIGS. 2 to 6.The 1,3-pentadiene derivatives can be employed in different ways, forexample, as shown in these figures.

In the photoconductor as shown in FIG. 2, a photoconductive layer 2a isformed on an electroconductive support 1, which photoconductive layer 2acomprises a 1,3-pentadiene derivative, a sensitizer dye and a binderagent. In this photoconductor, the 1,3-pentadiene derivative works as aphotoconductive material, through which charge carriers which arenecessary for the light decay of the photoconductor are generated andtransported. However, the 1,3-pentadiene derivative itself scarcelyabsorbs light in the visible light range and, therefore, it is necessaryto add a sensitizer dye which absorbs light in the visible light rangein order to form latent electrostatic images by us of visible light.

Referring to FIG. 3, there is shown an enlarged cross-sectional view ofanother embodiment of an electrophotographic photoconductor according tothe present invention. In the figure, reference numeral 1 indicates anelectroconductive support. On the electroconductive support 1, there isformed a photoconductive layer 2b comprising a charge generatingmaterial 3 dispersed in a charge transporting medium 4 comprising a1,3-pentadiene derivative and a binder agent. In this embodiment, the1,3-pentadiene derivative works as a charge transporting material; andthe 1,3-pentadiene derivative and the binder agent in combinationconstitute the charge transporting medium 4. The charge generatingmaterial 3, which is, for example, an inorganic or organic pigment,generates charge carriers. The charge transporting medium 4 accepts thecharge carriers generated by the charge generating material 3 andtransports those charge carriers.

In this electrophotographic photoconductor, it is basically necessarythat the light-absorption wavelength regions of the charge generatingmaterial 3 and the 1,3-pentadiene derivative not overlap in the visiblelight range. This is because, in order that the charge generatingmaterial 3 produce charge carriers efficiently, it is necessary thatlight pass through the charge transporting medium 4 and reach thesurface of the charge generating material 3. Since the 1,3-pentadienederivatives of the previously described general formula (I) do notsubstantially absorb light in the visible range, they can workeffectively as charge transporting materials in combination with thecharge generating material 3 which absorbs the light in the visibleregion and generates charge carriers.

Referring to FIG. 4, there is shown an enlarged cross-sectional view ofa further embodiment of an electrophotographic photoconductor accordingto the present invention. In the figure, there is formed on theelectroconductive support 1 a two-layered photoconductive layer 2ccomprising a charge generation layer 5 containing the charge generatingmaterial 3, and a charge transport layer 6 containing a 1,3-pentadienederivative of the previously described formula (I).

In this photoconductor, light which has passed through the chargetransport layer 6 reaches the charge generation layer 5 and chargecarriers are generated within the charge generation layer 5. The chargecarriers which are necessary for the light decay for latentelectrostatic image formation are generated by the charge generatingmaterial 3, accepted and transported by the charge transport layer 6. Inthe charge transport layer 6, the 1,3-pentadiene derivative mainly worksfor transporting charge carriers. The generation and transportation ofthe charge carriers are performed by the same mechanism as that in thephotoconductor shown in FIG. 3.

The electrophotographic photoconductor shown in FIG. 5, the chargegeneration layer 5 is formed on the charge transport layer 6 containingthe 1,3-pentadiene derivative in the photoconductive layer 2d, thus theoverlaying order of the charge generation layer 5 and the chargetransport layer 6 is reversed as compared with the electrophotographicphotoconductor as shown in FIG. 4. The mechanism of the generation andtransportation of charge carriers is substantially the same as that ofthe photoconductor shown in FIG. 4.

In the above photoconductor, a protective layer 7 may be formed on thecharge generation layer 5 as shown in FIG. 6 for protecting the chargegeneration layer 5.

When the electrophotographic photoconductor according to the presentinvention as shown in FIG. 2 is prepared, at least one 1,3-pentadienederivative of the previously described formula (I) is dispersed in abinder resin solution, and a sensitizer dye is then added to themixture, so that a photoconductive layer coating liquid is prepared. Thethus prepared photoconductive layer coating liquid is coated on anelectroconductive support 1 and dried, so that a photoconductive layer2a is formed on the electroconductive support 1.

It is preferable that the thickness of the photoconductive layer 2a bein the range of 3 μm to 50 μm, more preferably in the range of 5 μm to20 μm. It is preferable that the amount of the 1,3-pentadiene derivativecontained in the photoconductive layer 2a be in the range of 30 wt. % to70 wt. %, more preferably about 50 wt. % of the total weight of thephotoconductive layer 2a. Further, it is preferable that the amount ofthe sensitizer dye contained in the photoconductive layer 2a be in therange of 0.1 wt. % to 5 wt. %, more preferably in the range of 0.5 wt. %to 3 wt. %, of the total weight of the photoconductive layer 2a.

As the sensitizer dye, the following can be employed in the presentinvention: Triarylmethane dyes, such as Brilliant Green, Victoria BlueB, Methyl Violet, Crystal Violet, and Acid Violet 6B; xanthene dyes,such as Rhodamine B, Rhodamine 6G, Rhodamine G Extra, Eosin S,Erythrosin, Rose Bengale, and Fluorescein; thiazine dyes, such asMethylene Blue; cyanin dyes, such as cyanin; and pyrylium dyes, such as2,6-diphenyl-4-(N,N-dimethylaminophenyl) thiapyrylium perchlorate andbenzopyrylium salt (Japanese Patent Publication 48-25658). Thesesensitizer dyes can be used alone or in combination.

An electrophotographic photoconductor according to the present inventionas shown in FIG. 3 can be prepared, for example, as follows. A chargegenerating material in the form of small particles is dispersed in asolution of one or more 1,3-pentadiene derivatives and a binder agent.The thus prepared dispersion is coated on the electroconductive support1 and then dried, whereby a photoconductive layer 2b is formed on theelectroconductive support 1.

It is preferable that the thickness of the photoconductive layer 2b bein the range of 3 μm to 50 μm, more preferably in the range of 5 μm to20 μm. It is preferable that the amount of the 1,3-pentadiene derivativecontained in the photoconductive layer 2b be in the range of 10 wt. % to95 wt. %, more preferably in the range of 30 wt. % to 90 wt. %, of thetotal weight of the photoconductive layer 2b. Further, it is preferablethat the amount of the charge generating material 3 contained in thephotoconductive layer 2b be in the range of 0.1 wt. % to 50 wt. %, morepreferably in the range of 1 wt. % to 20 wt. %, of the total weight ofthe photoconductive layer 2b.

As the charge generating material 3, the following can be employed inthe present invention: Inorganic pigments, such as selenium, aselenium-tellurium alloy, cadmium sulfide, a cadmium sulfide - seleniumalloy and α-silicon; and organic pigments, for example, C.I. PigmentBlue 25 (C.I. 21180), C.I. Pigment Red 41 (C.I. 21200), C.I. Acid Red 52(C.I. 45100), and C.I. Basic Red 3 (C.I. 45210); azo pigments having acarbazole skeleton (Japanese Laid-Open Patent Application 53-95033), azopigments having a distyrylbenzene skeleton (Japanese Laid-Open PatentApplication 53-133445), azo pigments having a triphenylamine skeleton(Japanese Laid-Open Patent Application 53-132347), azo pigments having adibenzothiophene skeleton (Japanese Laid-Open Patent Application54-21728), azo pigments having an oxadiazole skeleton (JapaneseLaid-Open Patent Application 54-12742), azo pigments having a fluorenoneskeleton (Japanese Laid-Open Patent Application 54-22834), azo pigmentshaving a bisstilbene skeleton (Japanese Laid-Open Patent Application54-17733), azo pigments having a distyryl oxadiazole skeleton (JapaneseLaid-Open Patent Application 54-2129), azo pigments having a distyrylcarbazole skeleton (Japanese Laid-Open Patent Application 54-14967);phthalocyanine-type pigments such as C.I. Pigment Blue 16 (C.I. 74100);Indigo-type pigments such as C.I. Vat Brown 5 (C.I. 73410) and C.I. VatDye (C.I. 73030); and perylene-type pigments, such as Algo Scarlet B(made by Bayer Co., Ltd.) and Indanthrene Scarlet R (made by Bayer Co.,Ltd). These charge generating materials can be used alone or incombination.

An electrophotographic photoconductor according to the present inventionas shown in FIG. 4 can be prepared, for example, as follows. A chargegenerating material 3 is vacuum-evaporated on the electroconductivesupport 1, whereby a charge generation layer 5 is formed. Alternatively,a charge generating material 3 in the form of fine particles isdispersed in a solution of a binder agent, and this dispersion isapplied to the electroconductive support material 1 and then dried, and,if necessary, the applied layer is subjected to buffing to make thesurface smooth or to adjust the thickness of the layer to apredetermined thickness, whereby a charge generation layer 5 is formed.A charge transport layer 6 is then formed on the charge generation layer5 by applying a solution of one or more 1,3-pentadiene derivatives and abinder agent to the charge generation layer 5 and then drying theapplied solution. In this photoconductor, the charge generating materialemployed is the same as that employed in the photoconductor in FIG. 3.

It is preferable that the thickness of the charge generation layer 5 be5 μm or less, more preferably 2 μm or less. It is preferable that thethickness of the charge transport layer 6 be in the range of 3 μm to 50μm, more preferably in the range of 5 μm to 20 μm. In the case where thecharge generation layer 5 comprises a charge generating material in theform of fine particles, dispersed in a binder agent, it is preferablethat the amount of the charge generating material in the chargegeneration layer 5 be in the range of 10 wt. % to 95 wt. %, morepreferably in the range of about 50 wt. % to about 90 wt. % of theentire weight of the charge generation layer 5. Further, it ispreferable that the amount of the 1,3-pentadiene derivative contained inthe charge transport layer 6 be in the range of 10 wt. % to 95 wt. %,more preferably in the range of 30 wt. % to 90 wt. %, of the totalweight of the charge transport layer 6.

The electrophotographic photoconductor as shown in FIG. 5 can beprepared, for example, by coating a solution of the 1,3-pentadienederivative and a binder agent on the electroconductive support 1 anddrying the same to form a charge transport layer 6, and then coating onthe charge transport layer 6 a dispersion of finely-divided chargegenerating material, with addition thereto of a binder agent whennecessary, by spray coating, and drying the coated dispersion to form acharge generation layer 5 on the charge transport layer 6. The thicknessof each of the two layers 5 and 6 and the compositions thereof may bethe same as those of the photoconductive layer 2c in the photoconductorshown in FIG. 4.

When a protective layer 7 is formed on the charge generation layer 5 ofthe photoconductive layer 2e by coating an appropriate resin solution,for instance, by spray coating, the photoconductor as shown in FIG. 6can be prepared.

As the electroconductive support 1 for use in the present invention, ametal plate or metal foil, for example, made of aluminum, a plastic filmon which a metal, for example, aluminum, is evaporated, or paper whichhas been treated so as to be electroconductive, can be employed.

As the binder agent for use in the present invention, condensationresins, such as polyamide, polyurethane polyester, epoxy resin,polyketone and polycarbonate; and vinyl polymers such aspolyvinylketone, polystyrene, poly-N-vinylcarbazole and polyacrylamide,can be used. These resins can also be employed as a resin component inthe above mentioned protective layer 7.

Other conventional electrically insulating and adhesive resins can alsobe used as the binder agent in the present invention. When necessary,there can be added to the binder resins a plasticizer, for example,halogenated paraffin, polybiphenyl chloride, dimethylnaphthalene anddibutyl phthalate.

In the above described photoconductors according to the presentinvention, if necessary, an adhesive or barrier layer can be interposedbetween the electroconductive support and the photoconductive layer. Theadhesive layer or the barrier layer can be made of, for example,polyamide, nitrocellulose, or aluminum oxide. It is preferable that thethickness of the adhesive layer or barrier layer be 1 μm or less.

When copying is performed by use of the photoconductors according to thepresent invention, the surface of the photoconductor is chargeduniformly in the dark to a predetermined polarity. The uniformly chargephotoconductor is exposed to a light image so that a latentelectrostatic image is formed on the photoconductor. The thus formedlatent electrostatic image is developed by a developer to a visibleimage, and, when necessary, the developed image can be transferred to asheet of paper. The photoconductors according to the present inventionhave high photosensitivity and excellent flexibility.

Other features of this invention will become apparent in the course ofthe following description of exemplary embodiments, which are given forillustration of the invention and are not intended to be limitingthereof.

EXAMPLE 1

The following components were ground and dispersed in a ball mill toprepare a charge generation layer coating liquid:

    ______________________________________                                                           Parts by Weight                                            ______________________________________                                        Diane Blue (C.I. Pigment Blue                                                                        76                                                     25, C.I. 21180) (Charge generating                                            material of the formula in Table 3)                                           2% Tetrahydrofuran solution of                                                                     1,260                                                    a polyester resin (Trademark                                                  "Vylon 200" made by Toyobo Co.,                                               Ltd.)                                                                         Tetrahydrofuran      3,700                                                    ______________________________________                                    

This charge generation layer coating liquid was coated by a doctor bladeon the aluminum-deposited surface of an aluminum-deposited polyesterbase film, which served as an electroconductive support, so that acharge generation layer was formed on the electroconductive support witha thickness of about 1 μm when dried at room temperature.

Then the following components were mixed and dissolved, so that a chargetransport layer coating liquid was prepared:

    ______________________________________                                                           Parts by Weight                                            ______________________________________                                        1,3-Pentadiene derivative                                                                          2                                                        No. 32 in Table 1                                                             Polycarbonate resin (Trademark                                                                     2                                                        "Panlite K 1300" made by Teijin                                               Limited.)                                                                     Tetrahydrofuran      16                                                       ______________________________________                                    

The thus prepared charge transport layer coating liquid was coated onthe aforementioned charge generation layer by a doctor blade and driedat 80° C. for 2 minutes and then at 105° C. for 5 minutes, so that acharge transport layer with a thickness of about 20 μm was formed on thecharge generation layer. Thus, an electrophotographic photoconductor No.1 according to the present invention was prepared.

EXAMPLES 2 TO 31

Example 1 was repeated except that the charge generating material andthe 1,3-pentadiene derivative working as the charge transportingmaterial employed in Example 1 were respectively replaced by the chargegenerating materials and the 1,3-pentadiene derivatives as listed inTable 3, whereby electrophotographic photoconductors No. 2 to No. 31according to the present invention were prepared.

    TABLE 3        Charge   Transporting Photo-  Material conductor  (1,3-pentadiene No.     Charge Generating Material derivative No.)      1     ##STR169##      32      2     ##STR170##      32      3     ##STR171##      32      4     ##STR172##       32      5     ##STR173##      32      6     ##STR174##      32      7 β                                                           type     Copper Phthalocyanine 32      8     ##STR175##      28      9     ##STR176##       28  10 CG-1 28 11 CG-2 28 12 CG-1  2 13 CG-2  2 14 CG-1 58 15 CG-2 58     16 CG-1 13 17 CG-2 13 18 CG-1 33 19 CG-2 33 20 CG-1 34 21 CG-2 34 22     CG-1 35 23 CG-2 35 24 CG-1 44 25 CG-2 44 26 CG-1 61 27 CG-2 61 28 CG-1     58 29 CG-2 58 30 CG-1 23 31 CG-2 23 32 CG-1 20 33 CG-2 20

EXAMPLE 34

Selenium was vacuum-deposited with a thickness of about 1.0 μm on anabout 300 μm thick aluminum plate so that a charge generation layer wasformed on the aluminum plate.

A charge transport layer coating liquid was prepared by mixing anddispersing the following components:

    ______________________________________                                                           Parts by Weight                                            ______________________________________                                        1,3-Pentadiene derivative No. 32                                                                   2                                                        in Table 1                                                                    Polyester resin (Trademark                                                                         3                                                        "Polyester Adhesive 49000" made                                               by Du Pont Co.)                                                               Limited.)                                                                     Tetrahydrofuran      45                                                       ______________________________________                                    

The thus prepared charge transport layer coating liquid was coated onthe above-prepared selenium-deposited charge generation layer by adoctor blade, dried at room temperature and further dried under reducedpressure, so that a charge transport layer with a thickness of about 10μm was formed on the charge generation layer. Thus anelectrophotographic photoconductor No. 34 according to the presentinvention was prepared.

EXAMPLE 35

Example 34 was repeated except that selenium-deposited charge generationlayer with a thickness of about 1.0 μm was replaced by a chargegeneration layer comprising a perylene pigment having the followingformula with a thickness of about 0.6 μm, whereby an electrophotographicphotoconductor No. 35 was prepared. ##STR177##

EXAMPLE 36

A mixture of 1 part by weight Diane Blue (the same as employed inExample 1) and 158 parts by weight of tetrahydrofuran was ground anddispersed in a ball mill. To this mixture, 12 parts by weight of the1,3-pentadiene derivative No. 32 and 18 parts by weight of a polyesterresin (Trademark "Polyester Adhesive 49000" made by Du Pont Co.) wereadded and mixed, whereby a photoconductive layer coating liquid wasprepared.

The thus prepared photoconductive layer coating liquid was coated on analuminum-deposited polyester film by a doctor blade and dried at 100° C.for 30 minutes, so that a photoconductive layer with a thickness ofabout 16 μm was formed on the aluminum-deposited polyester film. Thus anelectrophotographic photoconductor No. 36 according to the presentinvention was prepared.

EXAMPLE 37

The same charge transport layer coating liquid as that prepared inExample 1 was coated by a doctor blade on the aluminum-deposited surfaceof an aluminum-deposited polyester base film, which served as anelectroconductive support, so that a charge transport layer was formedon the electroconductive support, with a thickness of about 20 μm whendried at room temperature.

Then the following components were ground and dispersed in a ball millto prepare a dispersion:

    ______________________________________                                                             Parts by Weight                                          ______________________________________                                        Bisazo pigment (a charge generation                                                                  13.5                                                   pigment "CG-2" shown in Table 3)                                              Polyvinyl butyral (Trademark "XYHL"                                                                  5.4                                                    made by Union Carbide Plastic                                                 Co., Ltd.)                                                                    Tetrahydrofuran        680                                                    Ethyl cellosolve       1020                                                   ______________________________________                                    

To the above dispersion, 1700 parts by weight of ethyl cellosolve werefurther added and the mixture was dispersed, whereby a charge generationlayer coating liquid was prepared.

The thus prepared charge generation layer coating liquid was coated onthe aforementioned charge transport layer by spray coating and dried at100° C. for 10 minutes, whereby a charge generation layer having athickness of about 0.2 μm was formed on the charge transport layer.

Then a methanol/n-buthanol solution of a polyamide resin (Trademark"CM-8000" made by Toray Industries, Inc.) was coated on the chargegeneration layer by spray coating and dried at 120° C. for 30 minutes,whereby a protective layer having a thickness of about 0.5 μm was formedon the charge generation layer. Thus an electrophotographicphotoconductor No. 37 according to the present invention was prepared.

The thus prepared electrophotographic photoconductors No. 1 to No. 37according to the present invention were charged negatively or positivelyin the dark under application of -6 kV or +6 kV of corona charge for 20seconds and then allowed to stand in the dark for 20 seconds withoutapplying any charge thereto. At this moment, the surface potentialV_(po) (V) of each photoconductor was measured by a Paper Analyzer(Kawaguchi Electro Works, Model SP-428). Each photoconductor was thenilluminated by a tungsten lamp in such a manner that the illuminance onthe illuminated surface of the photoconductor was 4.5 lux, so that theexposure E_(1/2) (lux·seconds) required to reduce the initial surfacepotential V_(po) (V) to 1/2 the initial surface potential V_(po) (V) wasmeasured. The results are shown in Table 4.

                  TABLE 4                                                         ______________________________________                                                 1,3-pentadiene          E.sub.1/2                                    Ex. No.  Derivative No. V.sub.po (V)                                                                           (lux sec)                                    ______________________________________                                         1       32             -1110    1.01                                          2       32              -990    1.20                                          3       32             -1220    1.40                                          4       32             -1130    1.25                                          5       32             -1036    1.02                                          6       32             -1210    1.00                                          7       32              -975    1.05                                          8       28             -1300    1.43                                          9       28             -1205    1.20                                         10       28             -1163    1.47                                         11       28             -1083    1.24                                         12        2             -1270    1.70                                         13        2             -1220    1.43                                         14       58             -1160    1.30                                         15       58             -1005    0.99                                         16       13             -1120    1.90                                         17       13             -1030    1.41                                         18       33             -1200    1.12                                         19       33             -1110    0.98                                         20       34             -1120    1.20                                         21       34              -975    0.97                                         22       35             -1040    1.05                                         23       35              -925    0.95                                         24       44             -1130    1.03                                         25       44             -1025    0.89                                         26       61             -1120    0.92                                         27       61             -1030    0.70                                         28       58             -1160    1.30                                         29       58             -1005    0.99                                         30       23             -1290    2.71                                         31       23             -1260    2.22                                         32       20             -1420    1.80                                         33       20             -1354    1.90                                         34       32              -850    3.01                                         35       32             -1270    3.20                                         36       32             +1350    1.20                                         37       32              +950    0.90                                         ______________________________________                                    

Each of the above electrophotographic photoconductors No. 1 through No.37 was incorporated in a commercially available electrophotographiccopying machine and a latent electrostatic image was formed thereon bybeing exposed to light image. The latent electrostatic image wasdeveloped with a dry-type developer to a visible toner image,electrostatically transferred to a transfer sheet made of plain paperand fixed thereto. As a result, a clear transferred image was obtainedby each of the photoconductors. When a liquid developer was employedinstead of the dry-type developer, clear transfer images were obtainedlikewise.

According to the present invention, not only the photoconductiveproperties, but also resistance to thermal and mechanical shock of theelectrophotographic photoconductors comprising an electroconductivesupport and a photoconductive layer formed thereon which comprises atleast one of the 1,3-pentadiene derivatives having the formula (I) inwhich R¹ and R² may be a methyl group at the same time are superior tothose of conventional photoconductors. Furthermore, the manufacturingcost of the above electrophotographic photoconductors according to thepresent invention is low.

What is claimed is:
 1. A 1,3-pentadiene derivative having formula (I):

    A--CH═CH--CH═CH--CH.sub.2 --A                      (I)

wherein: A represents ##STR178## in which Ar represents (a) a phenylenegroup which may be substituted with a substituent selected from thegroup consisting of an alkyl group having 1 to 4 carbon atoms and analkoxy group having 1 to 4 carbon atoms; (b) a biphenylene group; or (c)a naphthylene group which may be substituted with a substituent selectedfrom the group consisting of an alkyl group having 1 to 4 carbon atomsand an alkoxy group having 1 to 4 carbon atoms; R¹ and R² each represent(i) an alkyl group having 1 to 4 carbon atoms substituted with a phenylgroup which may be substituted with an alkyl group having 1 to 4 carbonatoms or an alkoxyl group having 1 to 4 carbon atoms or (ii) a phenylgroup which may be substituted with a substituent selected from thegroup consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxygroup having 1 to 4 carbon atoms, a halogen atom, and a phenyl group. 2.The 1,3-pentadiene derivative of claim 1, wherein at least one of R¹ andR² is phenylmethyl or phenyl.
 3. The 1,3-pentadiene derivative of claim1, wherein Ar is naphthylene.
 4. The 1,3-pentadiene derivative of claim1, wherein Ar is phenylene.